Gwyneth Paltrow and Stella McCartney Collab on Line for Goop

So what took best friends Gwyneth Paltrow and Stella McCartney so long to collaborate? It seems like a no brainer to most.

"We complement each other," Paltrow said. "It was the right time. We're very close friends. We were bringing two worlds together and it was important not to force them."

They created a capsule collection Paltrow's web site, Goop, that is devoted to a healthy lifestyle, beautiful things and delicious food. Some of the items in the Stella McCartney x Goop collection include of a classic black blazer, charcoal gray knit jumpsuit, black jeans and black wool trouser. McCartney's new Beckett handbag in black, gray and white will also be available. Prices start at $795 and launches on September 12th.

"It makes perfect sense. Stella and I keep our [collaborations] to a minimum," Paltrow said, explaining that both are extremely selective about the projects they choose.

"When one of your best friends is a very successful artist and you love and admire her work, you want to support it at all [costs]," Paltrow added. "I have this start-up, Goop, and I have a strong idea of what I want it to be. I went to Stella and asked if she would collaborate with me. She never had done a collaboration like this before until I strong-armed her. She's the most insanely amazing designer."

"I'm cringing," McCartney said, reacting to the praise. "Gwyneth has such a strong sense of style. One automatically recognizes what she likes to wear - very timeless and effortless pieces."